MEDFORD, Mass. (AP) — Democratic presidential hopeful Beto O’Rourke says a mandatory government buyback program for AK-47 and AR-15 rifles is needed because other gun control measures don’t do enough to remove weapons already on the streets.

O’Rourke spoke Thursday at Tufts University in his first campaign stop in Massachusetts. He said that while universal background checks and red flag laws that allow guns to be removed from those deemed a danger to themselves or others will save lives, neither will address the millions of assault-style weapons already in private hands.

He said the country needs to buy back those weapons.

“There are more than 10 million AR-15 and AK-47s on the streets of our communities today and so we must take the necessary though politically difficult step of saying that we have to buy those AR-15 and AK-47s,” O’Rourke said. “This is a mandate that every single American who owns one of them will have to fulfill.”

Last month, a gunman killed nearly two dozen people in O’Rourke’s El Paso, Texas, hometown using an AK-style rifle.

Other Democratic candidates for the White House have also vowed to crack down on the weapons.